热控系统对火力发电机组调峰运行性能影响的技术分析

在火力发电机组热控系统中,机组特性、控制方式和变工况都会对火力发电机组调峰运行性能造成影响,在制粉过程中会存在延迟响应,且很难克服延迟时间,需要在热控系统中添加热工保护功能,并对协调控制系统进行完善,进而让机组调峰能力得到提升,为火力发电热经济性提供保障。本文将结合实例,从机组特性、控制方式、变工况这3方面探讨热控系统对火力发电机组调峰运行性能影响的技术,并针对具体影响,提出一些优化改进机组控制的相应策略。     

基于流速仪法的柘林水电厂A1号机组效率试验研究

水轮机效率是评价水轮机性能的重要指标,是指导水电站经济运行的关键参数。江西柘林水电厂A1号机组服役时间长、老化严重,经专家论证后对其进行了改造。为了检验机组改造效果、鉴别设备的性能,对改造后的机组进行了原型效率试验研究。试验采用流速仪法测量机组在试验水头下的流速分布,利用平均流速法计算机组流量,测量出工作水头与机组出力,最终计算出原型机组效率并率定蜗壳流量系数。进而对测试结果进行整理分析,得到指导机组优化运行的性能曲线。试验结果验证了试验方法的可行性和准确性,且机组的更新改造达到设计要求。     

拖拉机深松机组匹配田间试验方法探讨及测试

针对目前我国深松作业机组匹配田间试验测试方法缺失的问题,分别从主要影响深松机组作业性能的6个方面进行田间试验方法简单探讨,并以某型拖拉机为例对该试验方法进行了验证和对该拖拉机深松机组性能进行了测试,为广大农机具工作者进行拖拉机深松机组匹配田间试验测试提供方法参考。     

基于模糊物元的泵站机组振动分析

文章以泵机组振动为例验证了这种评级方法的可行性与合理性,根据泵机组振动分析的评价指标体系建立了评价物元,依据对泵站机组振动的测试和评价进行统计并归一化处理来建立评价的参照物元,采用模糊层次分析法建立了评价权重物元,最终实现了泵机组振动性能的综合评价。     

飞来峡灯泡贯流式机组一次调频试验与分析

介绍了一次调频基本原理和技术要求,结合飞来峡水利枢纽大型灯泡贯流式机组一次调频功能完善,通过对调速器参数优化、调整以及机组并网运行实测,调频性能达到电网技术要求,进行了试验分析与评价,并提出机组运行相应意见,以资相关水电站同行试验、运行参考.     

蔺家坝灯泡贯流泵机组水力性能及结构分析

蔺家坝泵站作为我国首座采用齿轮箱传动的大型灯泡贯流泵机组的泵站,为使水泵装置具有较优的水力性能,采用CFD仿真技术对该灯泡贯流泵机组的流道进行了优化设计和计算,并与水泵装置模型试验结果进行了比较;重点分析了灯泡体的支撑结构、叶片调角机构、主轴密封装置、轴承布置、齿轮箱及同步电动机等主要设备的结构设计.结果表明：CFD仿真技术应用于灯泡贯流泵机组的水力性能优化是可行的,蔺家坝泵站采用大型灯泡贯流泵机组,在设计净扬程2.4 m工况下,水泵装置效率达到78%,且气蚀性能良好,技术参数均达到了南水北调东线工程的要求;大型齿联传动灯泡贯流泵机组的成功运行,为国内其他大流量低扬程泵站的机组选型、设计及制造提供了可借鉴的经验.     

泵站离心式机组并联调速运行特性分析

针对泵站系统变流量时泵站并联机组调速运行工况点难以确定的问题，分析了相同型号、相同管路布置时多泵并联的运行特性。在此基础上，通过简化管路约束，应用离心泵性能特性和流体机械相似原理对泵站多泵并联工作机组的运行特点进行了分析和研究，建立以系统流量为约束条件下的调速特性数学模型，讨论了多泵并联系统调速时的系统性能，并给出并联调速机组单泵调速情况下的工况点计算方法。     

提高牵引车—挂车机组跟踪性能的研究

对牵引车－挂车机组中挂车对牵引车运动轨迹的跟踪性能进行了探讨，建立了挂车车轮理论偏转角与联动机构几何关系的数学模型。通过样机对比试验证偏转挂车车轮的联动机构能有效地改善机组的轨迹跟踪性能，同时还改善了机组的通过性和机动性等。该联地动机构结构简单，实用，有一定的应用前景。     

如何合理利用农业机械的动力性能

根据农业生产的需要，将拖拉机与作业机械编成各种机组，以完成不同的农业作业项目。农机化作业一般是以机组的形式进行的，因此，研究农业机械的动力性能首先要研究机组的动力性能。     

拖拉机机组性能CAD系统结构与功能设计

对拖拉机机组性能CAD系统结构与功能进行了设计 ,提出了该CAD系统的各子系统的功能及作用 ,从而为开发一套集拖拉机及机组性能仿真分析基本理论及基于该理论的实用方法为一体的软件系统奠定基础 ,为我国拖拉机行业的产品性能分析和产品设计提供条件     

拖拉机阻力控制系统的辨识建模

建立了拖拉机阻力控制系统的室内模拟实验系统,通过分析与实验确立了系统模型结构,并进而运用系统辨识的方法建立了其完整的的模型,从而认定了该系统是一个含死区非线性环节的三阶闭环系统。     

Tillage Tool Design by the Finite Element Method: Part 2. Experimental Validation of the Finite Element Results with Soil Bin Test

Laboratory soil bin tests of subsoiler cutting in a sandy loam soil were carried out in order to validate the results obtained from the finite element calculations reported in Part 1 of this study. Measured results of subsoiler draught force and soil failure dimension taken on the surface were presented for four combinations of the subsoiler shank rake angle and chisel angle. Soil bin tests also measured the variation of draught force with subsoiler displacement. It was observed that the angle of both the subsoiler parts affected the dimensions of the surface soil failure and the magnitude of subsoiler draught force.Finite element method predictions of the subsoiler draught force as well as the extent of surface soil failure agreed well with measurements made in the soil bin. The predicted draught force for all subsoiler types exceeded the measured ones. The overprediction error ranged from 11·76 to 20·04%. The finite element model provided a good approximation to the maximum upward soil movement for the experiments. Better finite element method predictions of the front soil failure was obtained for the two subsoiler designs with a small chisel angle of 15° than for the designs with chisel angles of 23 and 31°. Among the four investigated subsoiler types the best subsoiler design was devised, which required the lowest draught and developed good soil loosening qualities as estimated by soil volume change. This subsoiler had a shank of 75° rake angle and an inclined chisel of 15° angle. Keeping a good soil loosening performance was attributed to the smaller shank rake angle of 75°, which indicated that the shank played an important role for the determination of the quality of soil loosening.     

一种新的纯牵引力传感装置

介绍了一种新的实现力调节系统纯牵引力传感的方法。对上拉杆传感的系统,在不改变原系统传感方式的前提下,可以有效地把作用在农具上的土壤力分解为垂直力和牵引阻力两部分,追到实现纯牵引力控制的目的。     

水质对膨润土防水毯防渗效果影响研究

针对我国西北干旱寒冷盐渍化地区渠道防渗存在的问题,对拟引进使用的膨润土防水毯的膨胀性能及防渗效果进行研究,提出推广应用一种新型复合土工合成材料（膨润土防水毯）。选择3种膨润土防水毯产品。采取室内试验,分析了不同浓度及离子溶液对膨润土防水毯防渗效果的影响。试验表明溶液浓度膨润土膨胀性能影响较大．当矿化度大于5g／L时膨胀量明显减小。离子及浓度对韩国1号（两层聚丙烯薄膜防护）防渗性能影响最小,除与膨润土成分及含量有关外,两层聚丙烯薄膜防护层结构对防渗性能也有较大的影响。     

丘陵旱地发展灌溉的研究

山西临汾地区的丘陵阶地,长期以来干旱缺水、土质脊薄、耕作粗放、产量不稳不高,这部分农田占该地区耕地的40％。为了改变这些地方的农业生产条件,需要发展农田灌溉。本文针对这一问题,经过几年的试验研究,从丘陵旱地发展灌溉的必要性、可行性、灌水技术选择、经济效益等方面进行了综合分析,提出了应以输水管道化和水池调蓄为主,充分利用当地小水源,采用节水型灌溉技术,并实行限额灌溉。     

被动式倾斜波纹圆盘破茬刀工作性能试验

以被动式倾斜波纹圆盘刀为研究对象,运用速度瞬心法得出播种机前进速度和切茬深度是切茬速度的主要影响因素。考察了播种机前进速度和配重对圆盘刀工作性能主要指标(切茬深度和牵引阻力)的影响。两指标两因素正交田间试验结果表明,切茬深度和牵引阻力均随两因素增加而增大,配重是影响切茬深度的主要因素;当配重达到一定值时,播种机前进速度对切茬深度的影响比对牵引阻力的影响显著。     

Force Measurements on Driven Discs

Experiments were carried out under controlled conditions in a soil bin containing sandy-loam soil to study the effects of varying the speed ratio (ratio of peripheral disc speed to forward speed), disc angle and tilt angle settings, on the performance of adriven disc. The hydraulically powered disc provided speed ratios from −3 (backward) through approximately 1 (free wheeling) to 6 (forward). Disc angles were varied from 20 to 65°, from the direction of travel, and tilt angles from −15 to 30° with respect to the vertical. It was observed that there was a major reduction in draught force and specific draught resistance in all cases when disc speed increased from freely rotating to forward speed ratios of approximately 3. Driving a disc in the reverse direction reduced penetration resistance at certain angle settings. Backward-driven discs were also found to reduce side forces on the concave side of the disc and increase those on the convex side. Total power consumption and specific total power increased significantly when the disc was driven in either direction. The angle setting also affected the driven-disc performance. The optimum angle setting in terms of minimizing force and power requirements occurred at a disc angle between 35 and 50° with approximately 0° tilt angle. Observations of soil disturbance showed that driving a disc either backward or forward improved soil mixing and pulverization characteristics.     

Some performance characteristics of disc gangs

The effect of number of discs in a gang on soil reaction forces was evaluated for gangs containing one to five discs. The performance of two different disc shapes was investigated, each at two operating angles. The angles and shapes were chosen to represent a wide range of operating parameters. Interaction was found to occur between discs; however, the interaction was not a function of the number of discs. The magnitude of the interaction was such that large errors would occur if gang draught force was calculated from single disc data only.     

A Novel Approach to the Prediction of Tillage Tool Draught using a Standard Tine

An investigation was conducted to develop and validate a novel approach to the prediction of the draught required by primary tillage implements op- erating in field conditions. A methodology was developed based upon an existing force prediction model which describes the draught of a standard tine as the product of two factors, related to soil strength and tool geometry respectively. The methodology results in a two-step prediction procedure, which consists of (1) establishing, in a reference soil condition, some comparative draught relationships (tool index I) be- tween the standard tine and each tillage implement and, (2) measuring the draught of the standard tine in the field. The tool index relationships were determined under laboratory conditions for a number of single tillage tools over a range of working depths, and the methodology was validated in four field conditions, namely: two friable sandy-loams, a compact clay and a plastic clay soil. Predicted draughts were on average within 18% of the measured values. In the friable soil conditions, the average prediction errors for the tine tools, mouldboard body and disc tool were 14%, 16% and 30% respectively. The corresponding errors for the same tools in the plastic clay were 18%, 26% and 26% respectively.     

Improvement of Planosol Solum: Part 1, Experimental Equipment,Methods and Preliminary Soil Bin Experiments with Ploughs

Based on field cultivation tests by Zhao and soil investigations by Araya, a one to one mixing of the second (Aw) and third (B) horizons was conducted to improve the planosol solum in China, leaving the first (Ap) horizon undisturbed. This paper deals with basic soil bin tests of soil mixing with half size model ploughs in Japan.The results showed that stand-up and drop-down ploughs produced good soil mixing and required low draught forces. On the other hand, a fold-up plough could not mix the soil and required a high draught force because the furrow slices did not move smoothly over the plough.